Hmmm. I have Win7 with 2 Gigs of Ram for quite some time and all my games are working fine (or maybe they don't but I can't realize it because I have no point of comparison).
I barely run stuff on the background, only my games and some apps. But for the record, at normal speed, stardard sized map, around turn 200 the turn times takes several seconds (I don't how much exactly, but just to throw a number it's around 30 seconds I guess). Sometimes (like each 5 turns) the game takes the usual 30 secs + 1 or 2 full minutes where the game freezes completely, so yeah, I believe it has something to do with the lack of memory.
Still, I thought that turn times where dependant on processing power, not Ram, that's why I ignored the latter for that long.
Thanks, I guess I'll need more memory